This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-078724, filed Mar. 21, 2000; and No. 2000-145384, filed May 17, 2000, the entire contents of both of which are incorporated herein by reference.
The present invention relates to an inkjet head used for forming desired images on printing media by ejecting ink drops toward the printing media such as a printing paper supplied to an inkjet printer, and particularly relates to an inkjet head removably supported by a head supporting member such as a carriage of a printer main body of the inkjet printer in order to ease an inspection and a maintenance of the inkjet head.
In a conventional inkjet printer, a head-side connecter is provided on an inkjet head, and an electric-current-supply-side connector is provided on a printer main body of the inkjet printer. The supply-side connector is connected to electric appliances in the inkjet printer. While the inkjet head is attached at a predetermined position on a head supporting member, the head-side connector is removably connected to the electric-current-supply-side connecter. When the inkjet head is removed from the head supporting member, the connection is cancelled.
The electric connection constitution as described above by which the inkjet head can be removably supported at the predetermined position on the head supporting member in the conventional inkjet printer is well-known by, for example, Japanese Patent Application KOKAI publication No. 5-16339. This conventional electric connection constitution is enlarged and schematically shown in FIG. 15 of the present application.
As shown in FIG. 15, the inkjet head supporting structure in the conventional inkjet printer is provided with a carriage 110 as a head supporting member, and the carriage 110 includes an inkjet head supporting base 112 having an inkjet head insertion port 112a. 
Into the inkjet head insertion port 112a, an inkjet head 114 is inserted. The inkjet head 114 is provided with an ink ejecting portion 114a, a head-side connector 114b arranged to oppose the ink ejecting portion 114a, and an electric connecting portion 114c made of a hard board and interposed between the inkjet ejecting portion 114a and the head-side connector 114b. 
The ink ejecting portion 114a, the head-side connector 114b, and the electrical connecting portion 114c are fixed at predetermined positions by a supporting cover (supporting body) 114d. 
More specifically, the ink ejecting portion 114a is fixed on one end of the supporting cover 114d, the head-side connector 114b is fixed on the other end of the supporting cover 114d, and the electric connecting portion 114c is arranged between the above described one end and the above described other end in a space covered by the supporting cover 114d. In the space covered by the supporting cover 114d, an ink supply pipe 114e is further arranged and extends from the ink ejecting portion 114a to the other end of the supporting cover 114d. On one end of the supporting cover 114d, an ink ejecting portion protecting portion 114f is further attached to surround the ink ejecting portion 114a. The head-side connector 114b has a plurality of guide projections 114g projecting in a direction opposite to the above described one end of the supporting cover 114d. 
At the end opposing the inkjet head insertion port 112a in the inkjet head supporting base 112, an electric-current-supply-side connector 116 is arranged. The supply-side connector 116 is connected to electric appliances of a printer main body through a circuit cable described later. More specifically, on an end surface 112b at a side opposing to an entrance of the inkjet head insertion port 112a, a plurality of guide projections 112c are provided to project therefrom. The electric-current-supply-side connector 116 has a plurality of insertion holes 116a into which the plurality of guide projections 112c can be inserted. The diameter of each of the plurality of insertion holes 116a is set sufficiently larger than that of each of the plurality of guide projections 112c. Therefore, the electric-current-supply-side connector 116 can be movable in directions crossing each of the plurality of guide projections 112c within a difference between the diameter of each of the plurality of insertion holes 116a and the diameter of each of the plurality of guide projections 112c. 
Around an outer circumferential surface of each of the plurality of guide projections 112c is wound a compression coil spring (urging means) 112d, so that the coil spring 112d is interposed between a projection end of each of the guide projections 112c and the end surface of the electric-current-supply-side connector 116. The compression coil springs 112d urge the electric-current-supply-side connector 116 toward the end surface 112b of the above described opposite side of the inkjet head supporting base 112.
In the carriage 110, a circuit cable 118 is arranged at a position away in the above described opposite direction from the end of the above described opposite side of the inkjet head insertion port 112a on the inkjet head supporting base 112. On the circuit cable 118, an electric circuit for controlling an operation of the ink ejecting portion 114a of the inkjet head 114 and an operation of the carriage 110 is constituted. From the circuit cable 118, a flexible printed circuit cable 120 extends to the electric-current-supply-side connector 116, and an extended end of the flexible printed circuit cable 120 is connected to the electric-current-supply-side connector 116.
In the carriage 110, an ink tank 122 is further arranged at a position away in the above described opposite direction from the end of the above described opposite side of the inkjet head insertion port 112a on the inkjet head supporting base 112. From the ink tank 122, an ink leading pipe 122a extends through the end of the above described opposite side of the inkjet head insertion port 112a into the inkjet head insertion port 112a of the inkjet head supporting base 112.
Into the inkjet head insertion port 112a (predetermined position for the inkjet head 114) of the inkjet head supporting base 112 in the carriage 110, the inkjet head 114 is inserted through the above described entrance with the head-side connector 114b being as a leading end. At this time, the plurality of the guide projections 114g of the head-side connector 114b are inserted into the plurality of guide holes 116a of the electric-current-supply-side connector 116, and the head-side connector 114b can be connected to the electric-current-supply-side connector 116 of the carriage 110 as shown by an arrow A in FIG. 15. Also, by the above insertion, the extended end of the ink leading pipe 122a from the ink tank 122 is inserted into the extended end of the ink supply pipe 114e of the inkjet head 114 and connected with it in the water-tight manner.
Insertion of the inkjet head 114 into the inkjet head insertion port 112a is stopped when a contact surface T of the ink ejecting portion protecting portion 114f of the inkjet head 114 is brought into contact with a positioning surface S surrounding the above described entrance of the inkjet head insertion port 112a in the inkjet head supporting base 112. In this state, the ink ejecting portion protecting portion 114f is fixed by a well-known fixing means on the positioning surface S of the inkjet head supporting base 112. More specifically, a plurality of through holes 114g are formed on the ink ejecting portion protecting portion 114f, and the above described fixing is performed by inserting a plurality of headed bolts not shown into these through holes 114g and screwing them into the positioning surface S.
The diameter of each of the plurality of through holes 114g is set larger than the diameter of a screw portion of each of the above described headed bolts not shown and is also set smaller than the diameter of a head portion of each of the above described headed bolts. Thus, while loosening the fixation of the ink ejecting portion protecting portion 114f against the positioning surface S by the above described headed bolts, the ink ejecting portion protecting portion 114f can be moved on the positioning surface S of the inkjet head supporting base 112 within a range of a clearance between the diameter of each of the plurality of through holes 114g and the diameter of the screw portion of each of the above described headed bolt not shown. And, by this movement, positions of a plurality of ink ejecting holes not shown of the ink ejecting portion 114a of the inkjet head 114 on the positioning surfaces S of the carriage 110 can be adjusted.
This position adjustment can be easily performed, because the electric-current-supply-side connector 116 can be moved on the above described other end of the inkjet head supporting base 112 within the limited distance as mentioned above in directions crossing each of the plurality of guide projections 112c and the electric connection between the circuit cable 118 and the electric-current-supply-side connector 116 in the carriage 110 is performed by a flexible printed circuit cable 120. Moreover, since the electric-current-supply-side connector 116 can easily follow a movement of the head-side connector 114b during the above described position adjustment, the electric connection between the electric connecting portion 114c of the inkjet head 114 and the circuit cable 118 of the carriage 110 will not be cancelled during the above described position adjustment.
However, in the conventional inkjet head 114 described above with reference to FIG. 15, the ink ejecting portion 114a, the head-side connector 114b, and the electric connecting portion 114c are electrically connected with each other with fixing a positional relation-ship between them, (that is, their positional relation-ship does not have a flexibility), because the electric connecting portion 114c is made of the hard board.
Thus, when the inkjet head 114 is inserted into and is removed from the inkjet head insertion port 112a (predetermined position) of the inkjet head supporting base 112, the head-side connector 114b of the inkjet head 114 is connected to and is disconnected from the electric-current-supply-side connector 116 of the inkjet head supporting base 112 so that a tensile force and a pushing force are applied to the electric connecting portion 114c and the head-side connector 114b. The tensile force and the pushing force may destroy an electric connection between the head-side connector 114b and the electric connecting portion 114c and/or an electric connection between the electric connecting portion 114c and the ink ejecting portion 114a, may cause a failure in the inkjet head 114, and may cause a displacement of the position of the ink ejecting portion 114a at the above described one end of the supporting cover 114d to reduce an image-printing accuracy.
Alternatively, in order to manufacture an inkjet head with an orientation of the head-side connector 114b different from that of the conventional inkjet head 114 shown in FIG. 15, an electric connecting portion with different shape or length from that of the electric connecting portion 114c shown in FIG. 15 should be newly prepared so that a manufacturing cost of the inkjet head which is different from the conventional one is increased.
Moreover, the conventional inkjet head supporting structure described above with reference to FIG. 15 requires a large space between the above described other end of the inkjet head supporting base 112 and the circuit cable 118 in the carriage 110, for a structure allowing the movement of the electric-current-supply-side connector 116 and for arranging the flexible printed circuit cable 112. Thus, in the above described conventional inkjet head supporting structure, a dimension along directions in which the inkjet head 114 is inserted into and removed from the inkjet head insertion port 112a is large.
The present invention is derived from the above circumstances, and an object of the present invention is to provide an inkjet head which prevents a load, applied to the inkjet-head-side connector when the inkjet head is mounted on or dismounted from a predetermined position in an inkjet printer, from transferring to other members including an ink ejecting portion and an electric connecting portion of the inkjet head, and which can reduce the probability of failure in the inkjet head and prevent an image-printing accuracy of the inkjet head from being lowered.
Another object of the present invention is to provide an inkjet head which can achieve the above described object, which can simplify the inkjet head supporting structure as compared to the conventional types, and which can make an outer dimension of the inkjet head supporting structure smaller than that of the conventional inkjet head supporting structure.
In order to achieve the above described objects of the present invention, an inkjet head according to the present invention comprises: a head body for ejecting ink; a flexible printed circuit cable, connected to the head body, for driving the head body; and a connector, connected to a position different from the head body on the flexible printed circuit cable, for receiving a signal for driving the head body from an external applicance, and for sending the signal to the flexible printed circuit cable, wherein the flexible printed circuit cable is bent between the head body and the connector and absorbs a tensile force and a pushing force both of which are applied to the connector.
When the inkjet head according to the present invention and constituted as mentioned above is used to form a desired image on a printing medium such as a printing paper, the printing head is mounted on a predetermined position of an inkjet head supporting structure of an inkjet printer main body and the head-side connector is connected to an electric-current-supply-side connector of the inkjet head supporting structure.
When the inkjet head is mounted on the predetermined position and is removed from the predetermined position, a pushing force and a tensile force are applied to the head-side connector and the electric-current-supply-side connector.
But, in the inkjet head according to the present invention and constituted as mentioned above, the tensile force and the pushing force are absorbed by the bent flexible printed circuit cable. As a result of this, an electric connection between the head-side connector and the flexible printed circuit cable and an electric connection between the flexible printed circuit cable and the head body are not destroyed, and a failure does not occur in the inkjet head. Further, when the head body of the inkjet head is dislocated or inclined from a predetermined position of the inkjet head, a position adjustment of the head body to the predetermined position can be performed easily because the head body and the head-side connector are connected by the flexible printed circuit cable, and an image-printing accuracy by the head body of the inkjet head does not be lowered.
In the inkjet head according to the present invention and constituted as mentioned above, the flexible printed circuit cable can be bent in any desired manner so that the connector and the head body are oriented in opposite directions, and so that the connector and the head body are arranged such that a straight line along a direction in which the connector is oriented crosses a straight line along a direction in which the head body is oriented.
In the inkjet head in which the flexible printed circuit cable is bent in the above described latter manner, various variations are easily provided that the connector is oriented in various directions to the head body, having the same constitutional members as those of the inkjet head with the flexible printed circuit cable bent as in the above described former manner.
In the inkjet head according to the present invention and constituted as mentioned above, the flexible printed circuit cable is in a shape extending between the head body and the connector, and the flexible printed circuit cable can be bent in a longitudinal direction of the flexible printed circuit cable so that the connector and the head body are oriented in opposite directions.
Alternatively, the flexible printed circuit cable in the shape extending between the head body and the connector, can be bent in a direction crossing a longitudinal direction of the flexible printed circuit cable so that the connector and the head body are arranged such that a straight line along a direction in which the connector is oriented can cross a straight line along a direction in which the head body is oriented.
The long and narrow flexible printed circuit cable can be bent easily at its a position between its both ends, and the bent flexible printed circuit cable is excellent in an efficiency for absorbing an external force applied thereto.
In order to achieve the above-mentioned latter object of the present invention, an inkjet head according to the present invention comprises: an ink ejecting portion to which ink is supplied and which ejects the supplied ink; a head-side connector for an electric connection with a connector of an external electric appliance in a removal manner; an electric connecting portion, interposed between the ink ejecting portion and the head-side connector, for electric connection between the ink ejecting portion and the head-side connector; and a head case for supporting the ink ejecting portion, the head-side connector and the electric connecting portion, wherein the head-side connector is supported by the head case so that the head-side connector is movable in the three-dimensional directions.
When the inkjet head according to the present invention and constituted as mentioned above is used to form a desired image on a printing medium such as a printing paper, the printing head is mounted on a predetermined position of an inkjet head supporting structure of an inkjet printer main body and the head-side connector is connected to an electric-current-supply-side connector of the inkjet head supporting structure.
When the inkjet head is mounted on the predetermined position and is removed from the predetermined position, a pushing force and a tensile force are applied to the head-side connector and the electric-current-supply-side connector.
But, in the inkjet head according to the present invention and constituted as mentioned above, since the head-side connector is supported by the head case so that the head-side connector is movable in the three-dimensional directions, the tensile force and the pushing force are absorbed by the above movement of the head-side connector. As a result of this, an electric connection between the head-side connector and the electric connecting portion is not destroyed, and a failure does not occur in the inkjet head. Further, when the ink ejecting portion (that is, the head body) of the inkjet head at the predetermined position of the inkjet head supporting structure of the inkjet printer is dislocated or inclined, the flexibility of the flexible printed circuit cable allows a smooth and easy dislocation or inclination of the ink ejecting portion to the flexible printed circuit cable and the head-side-connector, and an image-printing accuracy by the ink ejecting portion (that is, head body) of the inkjet head can be maintained easily. Moreover, compared to the conventional example that the electric-current-supply-side connector is supported at the predetermined position of the inkjet head supporting structure of the inkjet printer and is movable in the three-dimensional directions, the constitution of the inkjet head supporting structure can be simplified, and the outer dimension thereof can be made smaller than that of the conventional inkjet head supporting structure.
The inkjet head according to the present invention and constituted as mentioned above is preferably provided with an urging means, provided at the head case, for urging the head-side connector at the predetermined position of the inkjet head supporting structure of the inkjet printer toward the connector of the external electric appliance.
While the inkjet head according to the present invention is not arranged at the predetermined position of the inkjet head supporting structure of the inkjet printer and the head-side connector is not connected to the electric-current-supply-side connector of the external electric appliance, the head-side connector can be freely movable in the three-dimensional directions in the head case of the inkjet head and not stable. The above described urging means stably holds the head-side connector at a predetermined position in the head case of the inkjet head. As a result of this, when the inkjet head is arranged at the predetermined position of the inkjet head supporting body of the inkjet printer, the electric-current-supply-side connector of the external electric appliance can be easily connected to the head-side connector.
In the inkjet head according to the present invention and constituted as mentioned above, the electric connecting portion is preferably arranged between the ink ejecting portion and the head-side connector so that the electric connection portion is in capable of relative movement at least against the head-side connector and the electric connection portion allows the movement of the head-side connector in the three-dimensional directions.
With this constitution, the external force applied to the head-side connector as mentioned above is further weakened at the electric connecting portion.
At least a part of such an electric connecting portion has flexibility.
When at least a part of the electric connecting portion has elasticity, such an electric connecting portion can function as the above described urging means.
Such an electric connecting portion can omit an independent urging means, and makes the constitution of the inkjet head according to the present invention simple in comparison with a case where an urging means is formed independently of the electric connecting portion.
In order to achieve the above latter object of the present invention, an inkjet head according to the present invention is an inkjet head which is incorporated at a predetermined position of a supporting means of an inkjet printer and connected to an electric-current-supply-side connector, and which comprises an ink ejecting portion for ejecting ink; a head-side connector for removably connected to the electric-current-supply-side connector; a flexible printed circuit cable, interposed between the ink ejecting portion and the head-side connector, for electric connection between the ink ejecting portion and the head-side connector; and a case for housing the ink ejecting portion, the head-side connector and the flexible printed circuit cable, wherein the ink ejecting portion is fixed to the case and the head-side connector is held by the case so that the head-side connector is movable in the three-dimensional directions.
In another inkjet head according to the present invention and constituted as mentioned above, since the head-side connector is supported by the case so that the connector is removable in the three-dimensional directions, the tensile force and the pushing force applied to the head-side connector when the inkjet head is mounted on and dismounted from the predetermined position of the supporting means of the inkjet printer and the electric-current-supply-side connector are connected to and are disconnected from the head-side connector, is absorbed by the above described movement of the head-side connector. As a result, an electric connection between the head-side connector and the electric connecting portion is not destroyed, and a failure does not occur in the inkjet head. Further, the ink ejecting portion (that is, the head body) of the inkjet head at the predetermined position of the supporting means of the inkjet printer can be dislocated or inclined easily in order to improve an image-printing accuracy by the ink ejecting portion (that is, head body) of the inkjet head while the head-side connector is connected to the electric-current-supply-side connector.
The flexible printed circuit cable makes a movement of the head-side connector in each of the three-dimensional directions in the case of the inkjet head being more easy, an electric connection structure between the head-side connector and the ink ejecting portion (that is, head body) in the inkjet head being more simple, and, moreover, an electric connection work between them being more easy.
When the flexible printed circuit cable is movable between the ink ejecting portion and the head-side connector within the case, the flexible printed circuit cable further facilitates the movement of the head-side connector in each of the three-dimensional directions, and can better absorb an external force applied thereto from the head-side connector.
The above-mentioned movability of the flexible printed circuit cable is easily achieved by setting the length of the flexible printed circuit cable placed between the head-side connector and the ink ejecting portion being longer than the shortest distance between the head-side connector and the ink ejecting portion.
The above-mentioned movability of the flexible printed circuit cable is further easily achieved by bending the flexible printed circuit cable between the ink ejecting portion and the head-side connector within the case. This bending can be twice or more than twice.
Here, the flexible printed circuit cable can be bent so that the head-side connector and the ink ejecting portion are orientated in opposite directions, or can be bent so that the head-side connector and the ink ejecting portion are arranged such that a straight line along a direction in which the head-side connector is oriented crosses a straight line along a direction in which the ink ejecting portion is oriented.
The inkjet head in which the flexible printed circuit cable is bent in the above described latter manner easily provides various variations that the connector is oriented in various directions to the head body, having the same constitutional members as those of the inkjet head with the flexible printed circuit cable bent in the above described former manner.
The inkjet head is preferably provided with an urging means for urging the head-side connector outward.
While the inkjet head according to the present invention is not mounted at the predetermined position of the supporting means of the inkjet printer and the head-side connector is not connected to the electric-current-supply-side connector of the external electric appliance, the head-side connector can be movable in each of the three-dimensional directions in the case of the inkjet head and not stable. The above mentioned urging means stably holds the head-side connector at a predetermined position in the case of the inkjet head during the above described time. As a result of this, when the inkjet head is arranged at the predetermined position of the supporting means of the inkjet printer, the electric-current-supply-side connector of the external electric appliance can be easily connected to the head-side connector.
On the flexible printed circuit cable, an ink ejection driving integrated circuit for driving an ink ejection operation of the ink ejecting portion can be mounted.
In this way, since there is no need to provide the ink ejection driving integrated circuit around the predetermined position of the supporting means of the inkjet printer, a structure around the predetermined position can be simple.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.